#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 30

void error_handling(char *message);

int main(int argc, char *argv[]){
	int sock;
	char msg1[] = "Hi!";
	char msg2[] = "I'm another UDP host!";
	char msg3[] = "Nice to meet you";
	struct sockaddr_in your_adr;
	socklen_t your_adr_sz;

	if(argc != 3){
		printf("Usage : %s <IP><port> \n",argv[0]);
		exit(1);
	}

	sock = socket(PF_INET,SOCK_DGRAM,0);
	if(sock == -1){
		error_handling("socket error");
	}	
    //your_adr 通过客户端的命令行传递过来
	memset(&your_adr,0,sizeof(your_adr));
	your_adr.sin_family = AF_INET;
	your_adr.sin_addr.s_addr = inet_addr(argv[1]);
	your_adr.sin_port = htons(atoi(argv[2]));
	
	sendto(sock,msg1,sizeof(msg1),0,(struct sockaddr*)&your_adr,sizeof(your_adr));
	sendto(sock,msg2,sizeof(msg2),0,(struct sockaddr*)&your_adr,sizeof(your_adr));
	sendto(sock,msg3,sizeof(msg3),0,(struct sockaddr*)&your_adr,sizeof(your_adr));
	close(sock);
	return 0;
}

void error_handling(char *message){
	fputs(message,stderr);
	fputs("\n",stderr);
	exit(1);
}